From: Ömer F. USTA (omerusta@gmail.com)
Date: Fri 06 Jul 2007 - 02:15:05 EEST
X64 mimarisi ile x86 mirarisinin karþýlaþtýrýlmasýyla ilgili çok güzel
bir döküman
wikipedianýn sayfalarýnda mevcut :
http://en.wikipedia.org/wiki/X86-64
Benim x64 görünüþe göre sadece performanstan fazlasýný getiriyormuþ
Güvenlik konusunda böyle bir imkaný olduðunu bilmiyordum paylaþmak istedim :
No-Execute bit: The "NX" bit (bit 63 of the page table entry) allows
the operating system to specify which pages of virtual address space
can contain executable code and which cannot. An attempt to execute
code from a page tagged "no execute" will result in a memory access
violation, similar to an attempt to write to a read-only page. This
should make it more difficult for malicious code to take control of
the system via "buffer overrun" or "unchecked buffer" attacks. A
similar feature has been available on x86 processors since the 80286
as an attribute of segment descriptors; however, this works only on an
entire segment at a time. Segmented addressing has long been
considered an obsolete mode of operation, and all current PC operating
systems in effect bypass it, setting all segments to a base address of
0 and a size of 4 GiB. AMD was the first x86-family vendor to support
no-execute in linear addressing mode. The feature is also available in
legacy mode on AMD64 processors, and recent Intel x86 processors, when
PAE is used
On 7/6/07, Onur Küçük <onur@kablonet.com.tr> wrote:
>
> >Herhalde inteli'n de tamman 64 bit mimaride çalýþan iþelmciler
> >çýakrmasý ile care bulunabilecek bu soruna ancak.
>
> Aslýnda montecito dan beri IA-64 lerde donanýmsal olarak IA-32 desteði
> bulunmuyor. IA-32 (ya da adýna x86 vs. ne derseniz) instruction larý
> çalýþtýrmak için bir software emulation sistemi kullanmak gerekiyor.
>
> --
> Onur Küçük Knowledge speaks,
> <onur.--.-.kablonet.com.tr> but wisdom listens
>
> _______________________________________________
> Linux-programlama mailing list
> Linux-programlama@liste.linux.org.tr
> http://liste.linux.org.tr/mailman/listinfo/linux-programlama
>
-- Ömer Fadýl USTA http://www.bilisimlab.com/ _______________________________________________ Linux-programlama mailing list Linux-programlama@liste.linux.org.tr http://liste.linux.org.tr/mailman/listinfo/linux-programlama